Fingerprint sensors are sometimes used as “navigation tools”, for example to move a cursor or pointer on a display or to perform selections of items presented on a display etc.
To be able to use a fingerprint sensor for such a navigation tool application, it is necessary to somehow track movement of the finger of a user across the fingerprint sensor.
According to one approach, described in U.S. Pat. No. 6,408,087, ridges and pores of a fingerprint are identified and motion of the ridges and pores between successive images of the fingerprint is detected.
For accurate and fast fingerprint-based navigation, it would be desirable to provide for a very fast readout of navigation images. Unless the size of the navigation images is reduced, this would result in an increase in the current consumption, which is not acceptable for various important applications.
If the size of the navigation images is reduced, it may, however, be difficult or even impossible to reliably identify and track ridges and pores as is suggested by U.S. Pat. No. 6,408,087.
There is thus a need for an improved estimation of a finger movement using a fingerprint sensor, and in particular for a fingerprint-based navigation that works well with smaller navigation images.